. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 634 VICKI BUCHSBAUM PEARSE A. D 10 12 14 Days FIGURE 2. Percentage of anemones in lighted half of seawater table, after being initially distributed all in the shadowed half; (A-C) anemones with zooxanthellae when collected, from a sunny habitat, all from the same clone. (A.) Anemones with zooxanthellae showed a sig- nificant positive light response (at 5 days: x" = , P < , N = 52). (B.) Anemones having lost zooxanthellae after exposure to elevated temperature showed no significant light response (at 12 days:
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 634 VICKI BUCHSBAUM PEARSE A. D 10 12 14 Days FIGURE 2. Percentage of anemones in lighted half of seawater table, after being initially distributed all in the shadowed half; (A-C) anemones with zooxanthellae when collected, from a sunny habitat, all from the same clone. (A.) Anemones with zooxanthellae showed a sig- nificant positive light response (at 5 days: x" = , P < , N = 52). (B.) Anemones having lost zooxanthellae after exposure to elevated temperature showed no significant light response (at 12 days: X2=, P — , N = 41). (C.) Anemones having lost zooxanthellae after maintenance in darkness showed no significant light response (at 14 days: x2—, P — , N = 34). (D.) Anemones with zooxanthellae, from a shaded habitat (about 9% of light intensity measured in open intertidal), showed a significant negative light response (at 13 days: xs = , P < , N = 25). taxis as above, always occupied the shadowed half of the experimental area. If they were initially equally distributed between lighted and shadowed halves, they moved into the shadowed portion (Figure 1C). If initially placed entirely in the shadowed area, they remained there, none emerging into the light (Figure 2D). Light intensity The plasticity of behavior indicated by these results suggested the possibility that the anemones with zooxanthellae which I collected from shaded habitats, and which reacted negatively to the light intensity regularly used in the experiments (Figures 1C, 2D), might respond positively to a lower light intensity. To test this possibility, I selected anemones from a shaded habitat where midafternoon light readings were 200-250 foot-candles. Distributed randomly in a seawater table, these animals showed a negative response to the usual light intensity of 700 foot-candles, moving into the shadowed half of the table (Figure 3, left). After their distribution had remained s
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
